Method of making bimetallic elements



NOV. 22, 1933. J SMULSKl 2,137,309

METHOD OF MAKING BIMETALLIC ELEMENTS Original Filed Dec. 14, 1935 Zmventor 777e 0a'areu. Emu/ski 7 MW H13 Gttoineg.

Patented Nov. 22, 1938 UNITED STATES METHOD OF MAKING BIMIETALHC ELE- MENTS Theodore J. Smulski, Gary, Ind, assignor to The Anderson Company, Gar'y, Ind, a corporation of Indiana Original application December 14, 1933, Serial No. 702,341, now Patent No. 2,088,819. Divided and this application July 2, 1937, Serial No.

7 Claims. (01. 29-4555) This invention relates to bl-metallic elements, and methods for forming same for use in actuators for telemetric systems and similar purposes. I have illustrated in Patent Number 2,088,819, issued August 3, 1937 and entitled Actuators for telemetric systems apparatus embodylng an actuator operably responsive to liquid level and the like and a remotely disposed indicator registering changes in liquid level.

The said Patent Number 2,088,819 is directed to the actuator switch means whereas the present application is directed to bi-metallic means and method of forming same as embodied in the actuator switch means, the present application being a division of the said application which issued into said Patent No. 2,088,819.

The actuator to be hereinafter described includes a thermally responsive element operable by energization of a heatingcoil associated therewith and to compensate for changes in ambient temperature it is necessary to provide a second thermally responsive element related to the first element in such a manner that both elements will warp substantially equal amounts due to ambient temperature change to maintain a contact point relatively immovable under the influence of ambient temperature change.

Apparatus of. this type is necessarily sensitive in operation and its accuracy is largely dependent on the relation of the thermally responsive or bi metallic element. A slight variation of thermal characteristics in bi-metallic material is necessarily encountered in commercial production but I have found that this can be overcome if related bi-metallic elements are secured not only from a particular strip of material butfrom the same zone in such strip.

I have devised a method of manufacture whereby related bi-metallic elements of this type will necessarily be formed from the same zone of a particular strip and which is relatively inexpensive and adapts itself to large scale production.

It is an object of my invention therefore to provide ambient temperature compensating bimetallic elements having the same thermal characteristics.

Another object of my invention is to provide an improved method of forming related bl-metallic elements to be used in a thermally responsive switch.

Another object of my invention is to provide compensating thermally responsive elements having the same reaction to a common temperature change.

Another object of my invention is to provide an improved thermally responsive arrangement in an actuator for telemetric systems.

Other objects of my invention and the invention itself will become increasingly apparent from a consideration of the following description and drawing therein:

Fig. 1 is a front elevational view of a transmit ter or actuator embodying my invention, the view showing also a part of a liquid containing tank upon which the actuator is mounted;

Fig. 2 is a view of the actuator of Fig. 1 taken approximately from plane 2 of Fig. 1;

Fig. 3 is a view generally similar to Flg. 1 but with one of the frame elements thereof omitted to show interior mechanism thereof;

Fig. 4 is an enlarged top plan view of the actuator of Fig. 1 with a cover element removed to show interior mechanism;

Fig. 5 is a cross sectional view taken approximately from the plane 5 of Fig. 4 and with the removed cover element of Fig. 4 in place;

Fig. 6 is a view similar to Fig. 5 taken from the plane 6-6 of Fig. 4;

Fig. 7 is a fragmentary cross sectional view taken from the plane 7 of Fig. 4 and I Fig. 8 is a view of a pair of bi-metallic elements which I employ illustrating a step in the method of making the same.

Referring now to the drawing, and particularly to Fig. 1, I have shown generally at 0 an actuator mounted on a tank it and provided with a float 2' adapted to assume different elevated positions incorrespondence'with changes of liquid level it in the tank. Actuationbf the float it rocks a generally vertically extending lever Ml contacting a camming portion it associated with the float. The lever M is pivoted as indicated at it whereby the upper end of the lever will rock an arm H. The manner in which rocking motion is communicated to arm ill or the primary cause of the rocking motion whether it be change in liquid level, temperature change, or the like constitutes no essential part of my presentinvention and a more detailed description may be had by reference to the aforementioned Patent The and I1 has its upper end projected through a diaphragm l8 and secured thereto, the diaphragm covering a generally circular perforation provided in a cup-shaped element l9 permitting free rocking movement of arm 11. Rigidly secured to the portion of arm 11 projecting upwardly through diaphragm I8 is a contact element l9 comprising a laterally extending portlon and an upstanding portion provided with an electrical contact 20. Adjustably mounted on the base of cup element I9 is a. support element 2| having a transversely perforated upstanding portion 22 to which a link form bi-metallic element 23 'is adjustably secured by means of a rivet or the like.

Secured to the outer or free end of bi-metallic element 23 is a second link form bi-metallic ele- .ment 25, the bi-metallic elements being interconnected by disposing the end portions in overlapping relation and projecting a rivet or the like 26 through the perforations of both elements and subsequently heading over the rivet. The outer or free end for the bi-metallic element 25 is provided with an electrical. contact 21 engageable with the contact 20 of contact element IS. The bi-metallic elements 23 and 25 are adapted to warp substantially equal amounts in opposite directions at their free ends responsive to ambient temperature change and it willthereby be apparent that upon an ambient temperature change of a given amount, the free end of bi-metallic element 23 which is mounted on support element 2| will be moved a given amount and bodily move bi-metallic element 25 which is supported thereby, but since the free end of bimetallic element 25 is adapted to warp the same amount in an opposite direction, the relative position of contact 21 at the free end of bi-metallic element 25 will remain unchanged. Thus, variation in ambient temperature is compensated for by the above described construction and contact 21 is maintained in a given position.

Aheating coil 28 encircles bi-metallic element 25, one end of the coil being connected to contact 21 and the opposite coil end through a wire 29 being connected to a pair of contact prongs 30 which engage a terminal 3|.

Terminal 3| as best illustrated in Fig. 1 is connected by a wire 32 to an indicating instrument 33 and then by a wire 34 to a source of. power such as a battery 35, and then to 'a ground connection. The circuit is adapted to be completed upon engagement of the contacts, through the contact 20 associated with contact element l9 by traversing element 19, diaphragm l8, cup element I9 and a ground connection 36 at the tank.

Engagement of the contacts permits heating of coil 30 and this causes bi-metallic element 25 to become heated and warp away from contact 20 thereby separating the contacts and resultantly cooling the bi-metallic element 25 to again effect engagement of the contacts whereby a series of current impulses will be transmitted to the indicating unit 33 to give an indication of the relative position of the float element I2 and correspsndingly of liquid level in the tank. The particular circuit described constitutes no essential part of my present invention but it is merely illustrative of a use of bl-metallic elements arranged to compensate for ambient temperature.

The actuator above described must be sensithe to slight changes in liquid level to afford an 30 will effect corresponding changes in reading at the indicating unit 33. At the same time sufficient rigidity is provided in a vertical plane. Due to the fact that the bi-metallic elements must be necessarily sensitive in operation and equally responsive to ambient temperature change, the elements must have the same thermal characteristics. Different strips of bi-metal commercially available are not suificiently uniform in their thermal characteristics to fall within the limits desired and in fact, various parts of the same strip may vary sufliciently to be impractical for use in apparatus of this type. To insure that a pair of cooperating bi-metallic elements will have the same thermal characteristics, I sever them from the bi-metallic strips in connected form as illustrated in Fig. 8 whereby both elements are not only procured from the same strip but from the same area in a strip. Inasmuch as the width of the'oonnected bimetallic elements is substantially the same throughout, relatively little material is wasted other than that removed in forming the elongated slots in the elements.

The elements are maintained connected until they are ready to be assembled at which time they are severed at the point of connection, one of the elements is reversed, the elements are disposed in overlapping relation and a rivet projected through the perforated portions to interconnect the clements in final form. A variation of thermal characteristics between strips therefore is of no particular importance since the compensating movement of elements taken from a given strip will be the same.

Although I have illustrated and described a preferred form of my invention, I contemplate that numerous and extensive departures may be made therefrom without departing from the spirit of my invention and the scope of the ap pended claims.

I preferably punch av plurality of strips in one operation to the form shown in Fig. 8 since this practice lends itself to quantity production.

Having thus described my invention, what I claim is: e

1. The method of producing an ambient temperature compensated bi-metallic element of the type comprising a pair of bendable longitudinally aligned elements joined by an end of each, which includes stamping sheets of bi-metal in quantities from a blank comprising two longitudinally elongated elements joined at one end by a severable connecting neck of relatively-small cross section, subsequently'severing the neck, reversing one of the elements to reverse its direction of thermal bending, and then joining together the two elements at one end of each element.

2. The method of producing an ambient temperature compensated bi-metallicelement of the type comprising a pair of transversely bendable and longitudinally aligned elements joined at an end of each, which includes stamping from sheet bi-metal blanks comprising two longitudinally elongated elements joined at one end by a severable connecting neck of relatively small cross section, concurrently perforating each of said elements adjacent an end thereof, subsequently severing the elements at the neck, reversing one of the elements to reverse its direction of thermal bending, then-joining together the two ele ments by disposing them in overlapping relation and projecting a connecting element through the perforations.

3. The method of producing an ambient temperature compensated bi-metalllc element of the type comprising a. pair of transversely bendable and longitudinally aligned elements joined at one end of each, which includes stamping from sheet bi-metal blanks comprising two longitudinally elongated elements of link form and joined at one end by a severable connecting neck of relatively small cross section subsequently severing the neck, reversing one of the elements to reverse its direction of thermal bending, and then joining together the two elements at one end of each element.

4. The method of producing ambient temperature compensated bi-metallic elements for an electric switch, th: elements being of the type comprising a pair of bendable longitudinally aligned elements joined at one end, which includes stamping from sheet bi-metal blanks comprising two longitudinally elongated elements of link form joined at one end by a severable connecting neck and concurrently perforating one element adjacent an end thereof, subsequently severing the neck, reversing one of the elements to reverse its direction of thermal bending, then joining together the two elements at one end of each element, and securing an electrical contact at the perforated end of one of the elements.

5. The method of producing ambient temperature compensated bi-metallic elements for an electric switch or the like, the elements being of the type comprising a pair of bendable longitudinally aligned elements joined at an end of each, which includes stamping from sheet bi-metal blanks comprising two longitudinally elongated elements of link form joined by a neck portion,

subsequently severing the neck portion, reversing one of the elements to reverse its direction of thermal bending, and then joining together the elements at one end of each element by projecting a headed member through the elements and fianging a projected portion of said member.

6. The method of producing ambient temperature compensated bi 'metallic elements for an electric switch or the like, the elements being of the type comprising a pair of bendable longitudinally aligned elements joined at one end 01 each, which includes stamping from sheet bl-metal blanks comprising two longitudinally elongated elements of. link form-joined at one end of each by a severable neck, and with the ends of the elements remote from the neck substantially equally responsive to thermal change, subsequently severing the elements at the neck, reversing one of the elements to reverse its direction of thermal bending, overlapping the severed ends of the elements, to leave an opening 'therebetween, and securing the elements together by projecting a member through said opening and providing an abutment on the projected portion of said member.

7; The method of producing an ambient temperature compensated bi-metallic element of the type comprising a pair of bendable, longitudinally aligned elements joined by an end of each, which includes stamping from a sheet of bi-metal, a pair of elongated elements joined at an end of each by a' severable portion, subsequently severing the elements, reversing one of the elements to reverse its direction of thermal bending, and joining the elements together adjacent an end of each, whereby they may'bend in opposite directions responsive to thermal change from a plane substantially including the elements.

' THEODORE J. SMULSKI. 

